# Copyright 1999-2021 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

PYTHON_COMPAT=( python3_{8..10} )

inherit gstreamer-meson python-any-r1

DESCRIPTION="Hardware accelerated video decoding through VA-API plugin for GStreamer"

KEYWORDS="amd64 arm64 ppc64 ~riscv x86"
IUSE="+drm +egl gles2 +opengl wayland +X" # Keep default enabled IUSE in sync with gst-plugins-base and libva

# gst-vaapi configure is based around GL platform mainly, unlike gst-plugins-bad that goes by GL API mainly; for less surprises,
# we design gst-vaapi ebuild in terms of GL API as main choice as well, meaning that USE opengl and/or gles2 is required to
# enable opengl support at all and choices get chained from there.
# One or multiple video output are required: drm, x11, glx, egl and/or wayland;
# but GL API is our main trigger, thus USE=egl should be ineffective if neither gles2 or opengl is enabled;
# So "|| ( drm egl opengl wayland X )" would be wrong, because egl isn't built with USE="egl -opengl -gles2", ending up with no video outputs.
# As we ensure at least one working GL output with other REQUIRED_USE, we can put gles2/opengl in REQUIRED_USE instead of egl, solving the issue.
# gles2 API only supported windowing system (on linux) is EGL, so require it
# opengl API only supported windowing systems (on linux) are EGL and GLX, so require one of them (glx is enabled with USE="opengl X")
	|| ( drm gles2 opengl wayland X )
	gles2? ( egl )
	opengl? ( || ( egl X ) )

# glx doesn't require libva-glx (libva[opengl]) afaics, only by tests/test-display.c
# USE flag behavior:
# 'drm' enables vaapi drm support
# 'egl' enables EGL platform support (but only if also 'opengl||gles2')
# - 'egl' is exposed as a USE flag mainly to get EGL support instead of or in addition to GLX support with desktop GL while keeping it optional for pure GLX cases;
#   it's always required with USE=gles2, thus USE="gles2 opengl X" will require and build desktop GL EGL platform support as well on top of GLX, which doesn't add extra deps at that point.
# 'gles2' enables GLESv2 or GLESv3 based GL API support
# 'opengl' enables desktop OpenGL based GL API support
# 'wayland' enables non-GL Wayland support; wayland EGL support when combined with 'egl' (but only if also 'opengl||gles2')
# 'X' enables non-GL X support; GLX support when combined with 'opengl'
# gst-plugins-bad still needed for codecparsers (GL libraries moved to -base); checked for 1.14 (recheck for 1.16)
	drm? (
	gles2? ( ${GL_DEPS} )
	opengl? ( ${GL_DEPS} )
	wayland? ( >=dev-libs/wayland-1.11.0[${MULTILIB_USEDEP}] )
	X? (
		x11-libs/libXrender[${MULTILIB_USEDEP}] )


# FIXME: "Failed to create vaapipostproc element"

multilib_src_configure() {
	local emesonargs=(
		-Dwith_drm=$(usex drm yes no)
		-Dwith_x11=$(usex X yes no)
		-Dwith_wayland=$(usex wayland yes no)

	if use opengl || use gles2; then
		emesonargs+=( -Dwith_egl=$(usex egl yes no) )
		emesonargs+=( -Dwith_egl=no )

	if use opengl && use X; then
		emesonargs+=( -Dwith_glx=yes )
		emesonargs+=( -Dwith_glx=no )

	# Workaround EGL/eglplatform.h being built with X11 present
	use X || export CFLAGS="${CFLAGS} -DEGL_NO_X11"